Never heard of him.
Well, you should have done – the bond market may not be as well known to the world at large as the stock market, but it's where the real power lies these days. As the boss of the world's biggest bond fund manager, Mr Gross has the power to make or break companies or even countries.
Is he really so scary?
Put it this way: the reason George Osborne and friends are so desperate to cut spending and raise taxes is they're terrified the bond markets will lose confidence in Britain. Mr Gross – often described as the Warren Buffett of the bond world – has certainly added to that anxiety. Earlier this year he warned that gilts, UK government bonds, were "resting on a bed of nitroglycerine".
So what does he think now?
The gossip is that Pimco is reconsidering its views after a much stronger performance from gilts than it expected over the past six months.
You don't mean Mr Gross got it wrong for once?
It certainly seems that the collapse in gilt prices Pimco was expecting has not materialised. Still, they're smart folk over at Pimco: they didn't actually dump gilts, gambling instead on German bonds doing better, which they mostly have done.
What will he do with his latest winnings?
One of two things. He might spend a bit more on home improvements – having coughed up $23m for a waterside mansion in Newport Beach, California last year, he demolished it and has been rebuilding. Or he might buy a few more stamps. He's a renowned philatelist and one of only three owners of a complete collection of 19th century US postage stamps.
At least he hasn't got it in for us here in Britain any more.
He ought to be grateful really. He sold his British stamp collection for more than $9m a few years ago (donating the proceeds to Medecins Sans Frontieres). Maybe that's why Pimco took on a Briton as its European boss – one Andrew Balls, the brother of Ed Balls, Gordon Brown's sidekick at the Treasury for so long.